Semiconductor dies typically include a plurality of integrated circuits, bond-pads coupled to the integrated circuits, and metal routing layers for routing electrical signals between the bond-pads and external contacts. Fabricating and packaging such semiconductor dies include forming interconnects to electrically couple the bond-pads and/or metal routing layers to externally devices (e.g., a lead frame, a printed circuit board, etc.).
In some applications, the interconnects extend completely through or through a significant portion of the semiconductor dies (commonly referred to as “through-substrate interconnects”). One conventional process for forming through-substrate interconnects can include forming deep vias on the front and/or back side of a die in alignment with corresponding bond-pads. The vias are then filled with a conductive material (e.g., copper). Solder balls and/or other external electrical contacts are subsequently attached to the through-substrate interconnects.
The through-substrate interconnects may be formed (1) prior to integrating processing (commonly referred to as a “via-first” process), or (2) after the integration processing has been substantially completed (commonly referred to as a “via-last” process). However, both the via-first and via-last processes have certain drawbacks, as discussed in more detail later. Accordingly, several improvements to the process of through-substrate formation may be desirable.